This invention relates to electrical connectors and more particularly to an electrical connector having combined strain relief and insulation piercing characteristics.
Circuit concentration bays have been developed by the telephone company to handle the increased demand for additional telephone services and thereby provide improved methods of telephone traffic distribution. An interconnection system has been developed for circuit concentration bays utilizing a back panel and patch cord plugs. One side of the back panel is used for wire wrapping while on the other side of the panel provision is made for plugging in a patch cord plug.
The patch cord plugs are made up of one or more male pins and very small wire, i.e., in the order of 24 or 26 gauge, is either soldered or crimped to the pins. After the pins are made and connected to the wire, two plastic insulator halves are positioned on opposite sides of the male pins and are bonded together using ultrasonic bonding techniques.
Although a tool is generally provided for removing patch cord plugs from the back panel, it is sometimes necessary to pull a patch cord plug out by the wires. For this and other reasons, strain relief for the wires is necessary to prevent their being pulled loose from the pins. Therefore the patch cord plug has a built in strain relief that removes all strain from the interconnection of the wire to the pin. This strain relief is provided by a pair of ridges which are an integral part of the two piece insulator forming the housing.
A disadvantage of the aforementioned arrangement is that special tools are required to clamp and/or solder the pins to the wires. Also, special tools are required to bond the two insulator halves together. Additionally, two steps are required to assemble each patch cord plug. One step is required to solder or fasten each wire to each contact and a second step is required to bond the insulator halves together. Since a great number of plugs are required in the circuit concentration bays, the labor involved in these steps may be staggering.
A further drawback to the aforementioned patch cord plug design is that the patch cord plug is not reusable. If, for example, it is desired to change the connection of the wires to the pins, it is necessary to cut the wires from the plug and provide a new plug which of course must be reassembled in the manner discussed above.
A further problem in the aforementioned patch cord plug design is that the pair of strain relief ridges are provided in the housing and cause a transverse load on the housing when force is applied to the wires. As a result, special precautions in the form of multiple posts are required to rigidly attach and bond the insulator halves together.
Other types of electrical connectors are known which have insulation displacing cutters but which require special tools for applying pressure to force the cutters to pierce the insulation on the insulated conductor. One class of such electrical connectors has insulation piercing and strain relief in transverse overlapping portions of the metal contact.
Electrical connectors are also known in which the insulated conductor has its insulation automatically pierced or displaced as a housing for the connector is closed. However, these devices are normally quite large and do not permit use in back panel and patch cord plugs of the type employed in circuit concentration bays of the sizes referred to above. Further, the contacts themselves do not provide strain relief for the insulated conductor, this function being provided by the housing.